1. Field of the Invention
The invention relates to an engine exhaust cooling system, particularly for a marine diesel engine. The exhaust cooling system uses a small volume of water, which is atomized into a very fine mist. Due to atomization the mist vaporizes into steam. In one of its aspects, the invention relates to an engine exhaust cooling system utilizing the fine mist of water, efficiently convertible to steam, to take advantage of the latent heat of vaporization of steam to cool the exhaust flow.
2. Description of the Related Art
Modern marine diesel engines incorporate turbochargers for increasing the mass of intake air mixed with fuel for combustion. The turbocharger comprises a turbine driven by the exhaust gases of the engine itself. Efficient operation of the turbocharger requires that the exhaust gases be allowed flow freely, without the development of significant back pressure in the exhaust system. There is a requirement, however, for cooling the exhaust flow without the generation of high back pressure. In the past, water-cooled exhaust systems have used large orifices and higher pressures which resulted in a large volume of sea water entering the exhaust mixing chamber. The large water volume rendered the traditional mixing/water can very inefficient. As higher horsepower engines are being used and higher enthalpy is created, the demand for a more efficient cooling system is required.
A pollution control and cooling device for exhaust systems is known in U.S. Pat. No. 3,664,135 to Lirette, wherein a plurality of water streams are injected into an exhaust flow of a marine engine. The solid fine spray disclosed in Lirette creates a wall of substantial depth fully intersecting the exhaust as it emanates from an exhaust manifold. The introduction of a solid spray into an exhaust stream raises known issues, however, in that when the solid spray of water is introduced into the exhaust, very little of the water will flash to steam, creating high back pressures and very little temperature reduction in the exhaust system. Water in heavy streams serve as a heat sink capable of absorbing 1 BTU/lb for each degree Fahrenheit, whereas the latent heat of vaporization of water to steam is 970 BTU/lb.
It would be advantageous to provide an engine exhaust cooling system that efficiently cools the exhaust gases and does so without developing high back pressures in the exhaust system that will detrimentally effect the operation of an exhaust-driven turbocharger and the engine.
The invention relates to an engine exhaust cooling system for a marine diesel engine including a cooling water source, a cooling water manifold fluidly connected to the cooling water source, an exhaust conduit adapted to be fluidly connected to an exhaust outlet of a marine diesel engine, at least one fluid conduit fluidly connecting the cooling water manifold with the exhaust conduit, and at least one dispersion vane associated with the at least one fluid conduit, whereby water passing from the water manifold through the at least one fluid conduit strikes the at least one dispersion vane and develops a water mist for absorbing the latent heat of vaporization from the exhaust flow.
In a further embodiment, the at least one fluid conduit comprises an aperture through a wall separating the cooling water manifold and the exhaust conduit.
In a further embodiment of the invention, the at least one dispersion vane is aligned directly over the aperture.
In a further embodiment, the invention includes a first wall defining at least a portion of the exhaust conduit and at least a portion of the cooling water manifold.
In a further embodiment of the invention, the engine exhaust cooling system further comprises a second wall, wherein the at least one fluid conduit comprises an aperture through the second wall.
In a further embodiment of the invention, the at least one dispersion vane is aligned directly over the aperture.
In a further embodiment of the invention, the first wall is parallel to a longitudinal axis of the exhaust conduit. In a further embodiment of the invention, the engine exhaust cooling system further comprises a second wall, wherein the at least one fluid conduit comprises an aperture through the second wall. In a further embodiment of the invention, the at least one dispersion vane is arranged over the aperture.
In a further embodiment of the invention, the second wall describes an angle of 33 degrees with the plane of the first wall.
In a further embodiment of the invention, the dispersion vane comprises a planar sheet portion having a first edge aligned over the aperture.
In a further embodiment of the invention, the planar sheet portion is perpendicular to the second wall. In a further embodiment of the invention, the first edge is parallel to the second wall. In a further embodiment of the invention, the planar sheet portion further comprises a second edge aligned over the aperture. In a further embodiment of the invention, the second edge is perpendicular to the first edge.
A further embodiment of the invention relates to a marine internal combustion engine including a turbocharger having a turbine driven by exhaust gases generated by the engine, the turbocharger for generating compressed intake air for the engine, and an engine exhaust cooling system for cooling the exhaust gases after passage through the turbine, the cooling system including a water can having an inner cylindrical wall and an outer cylindrical wall concentric with the inner cylindrical wall, the inner and outer cylindrical walls being connected to each other by continuous upper and lower annular walls, the inner and outer cylindrical walls and the upper and lower annular walls defining a water manifold therebetween, a water source fluidly connected to the water manifold for supplying water to the water manifold, a plurality of apertures passing normally through the upper annular wall, and a plurality of dispersion vanes, each dispersion vane aligned over a corresponding one of the plurality of apertures, whereby water supplied by the water source to the water manifold passes through each of the plurality of apertures and strikes a corresponding dispersion vane.
In a further embodiment of the invention, the upper annular wall defines an angle of 33 degrees with a longitudinal axis of the water can.
A further embodiment of the invention relates to a marine craft driven by an internal combustion engine including a turbocharger having a turbine driven by exhaust gases generated by the engine, the turbocharger for generating compressed intake air for the engine, and an engine exhaust cooling system for cooling the exhaust gases after passage through the turbine, the cooling system including a cooling water source, a cooling water manifold fluidly connected to the cooling water source, an exhaust conduit fluidly connected to an exhaust outlet of the turbocharger, at least one fluid conduit fluidly connecting the cooling water manifold with the exhaust conduit, and at least one dispersion vane associated with the at least one fluid conduit, whereby water passing from the water manifold through the at least one fluid conduit strikes the at least one dispersion vane and develops a water mist for absorbing the latent heat of vaporization from the exhaust flow.